Carl august muller



llNiTnD Sintes Parent Ormea CARL AUGUST M'TLLER, OF NEV YORK, N. Y.,ASSIGNOR OF ONE-FOURTH TO OTTO BUHLER, OF SAME PLACE.

TRANSLUCENT FILM FOR USE IN THE ART 0F PHOTO-ENGRAVING.

SPECIFICATION forming part of Letters Patent No. 401,510, dated April16, 1889.

Applicationiiled May 28,1887. Serial No. 239,611. (Specimens.)

To all whom it may concern: exact reproduction, theoretically, of atinted' Beit known that l, CARL AUGUST MLLER, surface in pure lines andstipples is obtained,

of the city, county, and State of New York,have according to theprinciples of the art of phoinvented a certain new andusefulImprovetography. Consequently an entire picture is 55 5 ,ment inTranslucent Films for Use in the Art a mathematically-correctreproduction of a of Photo-Engraving, of which the followingl photographin minute grains, either lines or is a specification. stipples, if thecopied parts are considered as This invention relates to a method ofproabsolutely black portions. The parts which ducing impressions inlines or stipples from are produced in tints by the reproduction are 6o1o photographic negatives by reproducing the made non-transparent by anyof theknown body-shades or half-tones of the photograph chemicalprocesses used in the art of photogin an exact and perfect manner forthe purraphy and photo-chemistry, so thata negative pose of producingrelief-plates for the printor positive in grain or lines is obtained.Thus ing-press or tine lithographie work, to which a picture can beobtained by dusting the sen- 65 15 process I have given the name oftype-phositized plate with resin-powder and transfertography, as itsurpasses in the accurate rering the same to a stone or metal plate, and

production of the half-tones the reproduction it can be etched, &c.These means of transof the same in wood or other engravings. ferring,etching, and printing in lines or stip- For the purpose of changing aphotograph ples are well known to every photo-litho- 7o 2o of a naturalobject or work of art into a print graphic operator and photo-chemist,and reor engraving in lines or stipples, l copy any quireno furtherdescription. The grain which photographie negative or positive through ais obtained `by my method corresponds to the transparent iilm which iscovered with anumdifferent degrees of shades of the negative ber ofgeometrical figures, to which l have and positive. The greater thenumber of 7F 2 5 given the name of grain-figures. Each gradations oftints of which each grain-figure grain-figure is composed of a number ofgrais composed the better will the half-tones be dated shades or tints.The light passes reproduced. The smaller the number of through thenegative or positive and the transgradations of tints used in eachgrain-figure parent grain-film onto a sensitized plate unthe more willthe medium tints of the original 8o 3o til the proper degree ofintensity is produced he reproduced, so that the picture appears by eachgrain-ligure on said plate. By the consequently harder and crisper inthe halfinterposition of a transparent grain-film betones. tween thenegative or positive and the sensi- In the accompanying drawings, Figure1 tized plate each grain-figure dissolves the shows a negative havingseven gradations or S5 3 5 corresponding surface of the negative in itsshades of tint. O represents the first or white fundamental colors, withthe exception of the and transparent gradation, and 7 the last orhighest lights and deepest shades only in an more intense tint, whilethe intermediate grainverse ratio. Each grain-figure forms for dationscorrespond to different degrees of initself a gradated scale of alltints between tensity. The combined intensity of the first 4o thefundamental colors, black and white. The and sixth, for instance, isequal to the seventh different gradations or degrees of tints ofgradation, also that of the second and fifth, each grain-iigure are inexact proportion to thirdand fourth, &c. If this negative is crossed theratio of intensity in the saine manner as bya similar negative havingsiX gradations or the corresponding portion of the surface of shades oftints, but not including the seventh, 9 5 45 the negative is to thesurface of the grainthe diagramshown in FigzZis obtained, which figure,so that in copying a negative or posirepresents the degree of intensityof the intive through the transparent grain-film more tersecting scales,and which shows that the or less intensely-covered portions are formed,Zero gradation copies up to six, the iirst up which are at the inverseratio to the mixture to the fifth, the second up to the fourth, and 5oof the shades of the negative or positive. By so on, while the remainingtints assume the copying through a transparei'it grain-film an greatestdegree of intensity. The diminution i r l r of the tinted surface isequal to the increase of the ratio of intensity. The darkest parts arein the same ratio to the reproduced parts as t-he different gradationsof tints to the ratio of intensity. The mostintense parts are in thesame proportion to the reproduced parts as the ratio of the intermiXtureof the fundament-al colors, black and white, of the negative. This ratioof intermixture of a certain shade of tint forms also the theoreticalfoundation, which is followed in the reproduction of such a shade ortint by the art of the engraver.

The rules just stated determine the propor tion of the differentgradations and the size of the surface of each grain-figure, which canbe made in different geometrical configurations, as shown in Figs. 3 and4. Each grain-figure is composed of five, seven, or more differentgradations, which increase in intensity either from the center to theedges or vice versa, and the surface of each gradation is equal in areato either one of the remaining gradations. The exterior lines of eachgrain-ligure are also parts of the adjoining figures. The marginal line,which is either the next to the deepest shade or next to the highestlight of' each grain-ligure, forms also a part of the adjoininggrain-figures. The deepest degree of shade is excluded from eachgrain-figure, because it will be reproduced by the negative without theuse of the grain-iilms- For producing the transparent grain-films anumber of mathematically-exact grain-figures are first drawn on a largescale and reduced by photography to a smaller scale. This is againreduced to the degree of fineness required for the grain, as shown inFig. 5. From this negative having the necessary degreeof iineness ofgrain,- gelatine or other transparent films are made, which are used asthe transparent grainfilm in the manner before described. The grain canalso be produced by any of the known photographic-printing processes.These films containing my grain-gures are prepared ready made as anarticle of commerce and sale, and are made up in suitable quantities andused for carrying out my method of producing impressions vin lines orstipples from photographic negatives.

In place of gelatine, collodion or any other thin transparent medium canbe used, on which the grain-figures are directly produced by means ofthe negative or positive, which serves for reproducing the grain-figure.The film of grain-iigures may also be produced directly on the negativesor positives, in which case a still thinner film is obtained.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- A translucent film for use in the art ofphoto-engraving, provided with a numberof small grain-figures, eachligure being' composed of a series of bands of different shadesrepresenting different tints or tones, each band havingI the same shadethroughout its area, and the area of one band being equal to the area ofeach of the other bands, substantially as described.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

PAUL GOEPEL, CARL KARP.

